1. Field of the Invention
The present invention relates to a process for producing coated solid dosage forms by forming a plastic mixture comprising at least one polymeric binder and at least one active ingredient, and extruding the plastic mixture.
Coated solid dosage forms are being used increasingly frequently, in particular for pharmaceutical purposes. Examples of coated solid dosage forms are sugar-coated tablets, film-coated tablets, dry-coated tablets, multilayer film-coated tablets and multilayer sugar-coated tablets. Sugar- and film-coated tablets are obtained by treating (coating) an active ingredient-containing binder (e.g. granules, tablet) with suitable film-forming substances intended to mask the taste of the active ingredients, increase the stability to moisture and on storage, and facilitate identification. However, the active ingredient release characteristics can also be influenced by suitable choice of the coatings. In the case of dry-coated tablets, multilayer film-coated tablets or multilayer sugar-coated tablets there is compression together of several layers of binder, as a rule in elaborate, usually multistage processes, in tableting machines. The different layers usually contain different active ingredients or active ingredients in different concentrations in order to make it possible to administer incompatible active ingredients together and/or specifically influence the release characteristics. The processes for producing such solid dosage forms are generally elaborate, multistage and therefore time-consuming and costly.
2. Description of the Related Art
A considerably simpler continuous process for producing solid drug forms has been known for some time and entails extruding a solvent-free melt of a polymeric binder containing active ingredients, and shaping this extrudate to the required drug form, for example in a calender with molding rolls, see, for example, EP-A-0 240 904 and EP-A-0 240 906. It is possible with this process to produce solid combination drug forms as described in WO 97/15293. The production of multilayer solid drug forms using this process takes place by coextrusion as described in DE 197 10 213.1, but this process is only conditionally suitable for processing the high-viscosity binders which are important for interior phases or layers for producing very slow release dosage forms because they may easily lead to blockage of the molding dies. WO 96/19963 describes a process for producing encased tablets by melt calendering, wherein the active ingredient-containing melt is introduced between two sheets of the encasing material into the calender molding rolls. However, this process is confined to thermoplastic coating compositions which can be processed as sheets.
It is an object of the present invention to provide a continuous process for producing coated solid dosage forms which also permits the use of high-viscosity binders for interior layers and the use of a large number of coating agents.
We have found that this object is achieved by a plastic mixture being formed from at least one thermoplastic polymeric binder and at least one active ingredient and being extruded, the extrudate being treated in a second step with at least one liquid or vaporized coating agent, and subsequently the shaping being carried out.